In general, a vehicle includes a vehicle body and a chassis. The vehicle body forms the external appearance of the vehicle, and the chassis is a part in which mechanical devices are installed.
As a constituent element of the vehicle body, side structures such as a side inner panel, a side outer reinforcement panel, not only maintain the external appearance of a lateral side of the vehicle body, but also protect passengers from external impact by increasing rigidity of the lateral side of the vehicle body.
In recent years, as interests in safety for passengers with more restrictions become higher, research has been actively conducted to improve safety for passengers by reinforcing a lateral side portion of the vehicle body, which is more vulnerable to an external impact than a front side or a rear side of the vehicle body during a car accident.
Referring to FIG. 1, a method of assembling the vehicle body in the related art at the time of a side sub assembly includes a side inner panel (not illustrated), a side outer reinforcement panel 2 coupled to an outer portion of the side inner panel, a side outer inner panel 3, and a side outer panel 4 assembled in advance in a main buck process, and then assembled with a floor 1 and roof rails 5, and a roof panel 6 on an upper portion of the vehicle body.
However, as illustrated in FIGS. 1 to 3, when the side structures and the roof rails 5 are coupled to each other by using the method in the related art, connecting portions between the side structures and the roof rails are formed in a simple flange joint without having a cross section, and thereby a side inner reinforcement part 7 is disconnected from the roof rails 5 without being connected to the roof rails 5.
The lateral side portion of the vehicle therefore is excessively deformed at the time of collision and rigidity test, and thereby safety for the passengers may not be secured.
Referring to FIG. 2A, an extension panel 9 having welding holes 8 is coupled to the connection portions between the side structures and the roof rails 5 in order to solve the aforementioned structural problem and improve performance.
However, the size of a component becomes large and the weight of the vehicle is increased as the extension panel 9 is added to the connection portions between the side structures and the roof rails, and welding performance deteriorates because of the addition of the welding holes.